A conventional light device for refrigerators or freezers is shown in FIG. 4 and generally includes a rotatable switch 6, an interior light 61 and an exterior light 62 which is electrically connected to the interior light 61 in parallel. The switch 6 is a two-stage operation switch so as to respectively control the interior light 61 and the exterior light 62. The switch 6 is manually rotated to the first stage of rotation to let the exterior light 62 light up and then the interior light 61 is lighted up by continuously rotating the switch 6 to second stage of operation. By this way, the products in the freezer can be seen by the customers and the exterior light 62 provides a bright shopping mood. However, the interior and exterior light 61, 62 does not automatically turn off when no customers to visit the freezer and electrical power is wasted during the period.